A disk brake apparatus includes a disk rotor to be fixed to an axle, a disk brake friction pad assembly constituted of a torque receiving plate disposed opposed to the disk rotor and a lining member assembled to the disk rotor side surface of the torque receiving plate, and a brake caliper to be fixed to a vehicle body frame and including therein an actuator for advancing and retreating the torque receiving plate with respect to the disk rotor, whereby a braking force is generated by sliding friction caused when the torque receiving plate is advanced toward the disk rotor to thereby press the lining member against the disk rotor.
In a disk brake apparatus for a railway vehicle, since a disk rotor and a friction pad assembly for a disk brake are large in size, when a lining member to be pressed against the disk rotor is formed of an integral part, such area of the lining member as is not contacted with the disk rotor is increased due to the undulation of the disk rotor caused by frictional heat or the like, whereby stable frictional area cannot be maintained and thus stable braking characteristics cannot be provided.
Also, when the lining member is rotated unexpectedly due to contact with the disk rotor, the loss transmission of the braking torque can occur and braking noises can occur. This causes the need of a device for restricting the rotation of the lining member, which increases the number of parts. The increased number of parts incurs the increased cost and the increased the number of assembling steps, thereby lowering the productivity.
In solving such problem, there is provided a friction pad assembly for a disk brake, comprising: a plurality of lining assemblies swingably (oscillatably) supported by a guide plate to be pressed against a disk rotor each including, in its back plate portion fixed to the back surface of a friction member, a plate engaging section having an outer peripheral surface swingably engaged with a guide hole section formed in the guide plate and a retaining flange section having a larger outer diameter than the guide hole section, thereby transmitting braking torque acting due to contact between the disk rotor and friction member from the plate engaging section to the guide plate; and, a plurality of link plates interposed between the back plate portion and a torque receiving plate fixed to the guide plate with a clearance from the back plate portion and straddling over the plurality of lining assemblies for applying pressure from the torque receiving plate to the lining assemblies (see the patent reference 1).
In the thus-structured friction pad assembly for a disk brake, each link plate includes a single contact curved face to be contacted with and swingably supported by the link support portion of the torque receiving plate, plurality of back plate contact curved faces to be contacted with the centrally situated link contact section of the back plate portion of each lining assembly for supporting the lining assembly swingably, and a rotation regulating portion loosely engageable with an engaging hole formed in the back plate portion of each lining assembly at a position distant from the center thereof for regulating the swing motion of each lining assembly.
That is, since the member for receiving the braking torque from the lining assembly and the member for applying the pressure to the lining assembly are provided separately, the braking torque providing a large load is not applied to contact portions where the plate contact curved faces and back plate contact curved faces for applying the pressure to the lining assemblies are contacted with the torque receiving plate. Therefore, the contact portions for transmitting the pressure need not be engaged by a firm engaging device such as a ball joint for receiving the braking torque. Thus, the working precision can be eased to thereby realize the reduced cost and enhanced productivity.
Also, since the rotation regulating portion for regulating the swing motion of the lining assemblies is realized by the engagement between the engaging holes of the back plate portions and the rotation regulating portions projects on the link plate, there can be avoided the occurrence of inconveniences such as the increased cost caused by the increased number of parts and the lowered productivity due to the increased number of assembling steps.